Systems and methods are disclosed and include a method that includes adding a training symbol prefix to an OFDM symbol frame, the prefix including a plurality of training symbols, each including N sub-symbol fields. N/2 of the sub-symbol fields are zero valued, and N/2 of the sub-symbol fields carry corresponding symbols of a N/2 sub-symbol pseudo random training symbol. A first half of the pseudo random training symbol is symmetrical to a second half of the pseudo random training symbol. An OFDM N-sub-carrier transmission carries the prefix as signal power on a first N/2 of its N sub-carriers and suppresses signal power on a second N/2 of the sub-carriers. The first N/2 and second N/2 sub-carriers alternate in the frequency domain.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A system for synchronizing a receiving of an orthogonal frequency division multiplexing (OFDM), the system comprising: an input data interface configured to receive a sequence of signal samples; a processing unit; and a memory configured to a store a plurality of instructions that when read and executed by the processing unit cause the processing unit to: generate a pseudo-random sequence of N/2 sub-symbols, a first half of the pseudo-random sequence being symmetrical to a second half of the pseudo-random sequence; form an N sub-symbol training prefix that includes N/2 arithmetic zero values interleaved with the pseudo-random sequence of N/2 sub-symbols; and transmit the N sub-symbol training prefix as an N sub-carrier training transmission, in association with transmitting an OFDM frame, wherein: the N sub-carrier training transmission carries signal power on a first N/2 of the N sub-carriers and suppressed power on a second N/2 of the N sub-carriers, the first N/2 sub-carriers and the second N/2 sub-carriers being aligned at alternating positions in the frequency domain, and the first N/2 sub-carriers correspond to the pseudo-random sequence of N/2 sub-symbols and the second N/2 sub-carrier correspond to the arithmetic zero values.
2. The system of claim 1 , wherein: each of the N/2 sub-symbols of the pseudo random sequence is a complex value, corresponding to an X-Y position in a complex plane, X being an in-phase component and Y being a quadrature component, and the N sub-carrier training transmission includes, for each pseudo-random sequence of N/2 sub-symbols included in the N sub-symbol training prefix, an amplitude-phase modulation of one of the first N/2 sub-carriers.
3. The system of claim 1 , wherein the N sub-carrier training transmission comprises: inputting the N sub-symbol training prefix to an N-point inverse Fourier Transform process, and outputting a corresponding N time domain samples, and transmitting, as the N sub-carrier training transmission, the N time-domain samples.
4. The system of claim 3 , wherein: the N-point inverse Fourier Transform process outputs the corresponding N time domain samples in a parallel arrangement, and transmitting the N time-domain samples includes a parallel-to-serial re-configuration on the outputs Fourier Transform process into a serial stream of the N time domain samples, and a transmitting of the serial stream.
5. The system of claim 1 , wherein the N sub-symbol training prefix includes the N/2 arithmetic zero values at respective N/2 odd positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 even positions of the N sub-symbol training prefix, the N/2 even positions being interleaved with N/2 odd positions.
6. The system of claim 1 , wherein the N sub-symbol training prefix includes the N/2 arithmetic zero values at respective N/2 even positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 odd positions of the N sub-symbol training prefix, the N/2 odd positions being interleaved with N/2 even positions.
7. The system of claim 1 , wherein the N sub-symbol training prefix is a first N sub-symbol training prefix, the N sub-carrier training transmission is a first N sub-carrier training transmission, and the pseudo-random sequence of N/2 sub-symbols is a first pseudo-random sequence of N/2 sub-symbols, and wherein plurality of instructions further includes instructions that when read and executed by the processing unit cause the processing unit to: generate a second pseudo-random sequence of N/2 sub-symbols, a first half of the second pseudo-random sequence being symmetrical to a second half of the second pseudo-random sequence; form a second N sub-symbol training prefix that includes a second N/2 arithmetic zero values interleaved with the second pseudo-random sequence of N/2 sub-symbols; and transmit the second N sub-symbol training prefix as a second N sub-carrier training transmission, in association with transmitting the OFDM frame, wherein: the second N sub-carrier training transmission carries, at alternating positions in the frequency domain, signal power on a first N/2 of the N sub-carriers of the second N sub-carrier training transmission and suppressed power on a second N/2 of the N sub-carriers of the second N sub-carrier training transmission, and the first N/2 sub-carriers and the second N/2 sub-carriers of the N sub-carriers of the second N sub-carrier training transmission correspond, respectively, to the second pseudo-random sequence of N/2 sub-symbols and the second N/2 arithmetic zero values.
8. A method for communicating a robust synchronization orthogonal frequency division multiplexing (OFDM) frame, comprising: generating a pseudo-random sequence of N/2 sub-symbols, a first half of the pseudo-random sequence being symmetrical to a second half of the pseudo-random sequence; forming an N sub-symbol training prefix that includes N/2 arithmetic zero values interleaved with the pseudo-random sequence of N/2 sub-symbols; and transmitting the N sub-symbol training prefix as an N sub-carrier training transmission, in association with transmitting an OFDM frame, wherein: the N sub-carrier training transmission carries signal power on a first N/2 of the N sub-carriers and suppressed power on a second N/2 of the N sub-carriers, the first N/2 sub-carriers and the second N/2 sub-carriers being aligned at alternating positions in the frequency domain, and the first N/2 sub-carriers correspond to the pseudo-random sequence of N/2 sub-symbols and the second N/2 sub-carrier correspond to the arithmetic zero values.
9. The method of claim 8 , wherein: each of the N/2 sub-symbols of the pseudo random sequence is a complex value, corresponding to an X-Y position in a complex plane, X being an in-phase component and Y being a quadrature component, and transmitting the N sub-symbol training prefix as the N sub-carrier training transmission the N sub-carrier training transmission includes, for each pseudo-random sequence of N/2 sub-symbols included in the N sub-symbol training prefix, amplitude-phase modulating of one of the first N/2 sub-carriers.
10. The method of claim 8 , wherein transmitting the N sub-symbol training prefix as the N sub-carrier training transmission comprises: inputting the N sub-symbol training prefix to an N-point inverse Fourier Transform process, and outputting a corresponding N time domain samples, and transmitting, as the N sub-carrier training transmission, the N time-domain samples.
11. The method of claim 10 , wherein: the N-point inverse Fourier Transform process outputs the corresponding N time domain samples in a parallel arrangement, and transmitting the N time-domain samples includes a parallel-to-serial re-configuration on the outputs Fourier Transform process into a serial stream of the N time domain samples, and a transmitting of the serial stream.
12. The method of claim 8 , wherein the N sub-symbol training prefix includes the N/2 arithmetic zero values at respective N/2 odd positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 even positions of the N sub-symbol training prefix, the N/2 even positions being interleaved with N/2 odd positions.
13. The method of claim 8 wherein the N sub-symbol training prefix includes the N/2 arithmetic zero values at respective N/2 even positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 odd positions of the N sub-symbol training prefix, the N/2 odd positions being interleaved with N/2 even positions.
14. The method of claim 8 , wherein the N sub-symbol training prefix is a first N sub-symbol training prefix, the N sub-carrier training transmission is a first N sub-carrier training transmission, and the pseudo-random sequence of N/2 sub-symbols is a first pseudo-random sequence of N/2 sub-symbols, and wherein the method further comprises: generating a second pseudo-random sequence of N/2 sub-symbols, a first half of the second pseudo-random sequence being symmetrical to a second half of the second pseudo-random sequence; forming a second N sub-symbol training prefix that includes a second N/2 arithmetic zero values interleaved with the second pseudo-random sequence of N/2 sub-symbols; and transmitting the second N sub-symbol training prefix as a second N sub-carrier training transmission, in association with transmitting the OFDM frame, wherein: the second N sub-carrier training transmission carries, at alternating positions in the frequency domain, signal power on a first N/2 of the N sub-carriers of the second N sub-carrier training transmission and suppressed power on a second N/2 of the N sub-carriers of the second N sub-carrier training transmission, and the first N/2 sub-carriers and the second N/2 sub-carriers of the N sub-carriers of the second N sub-carrier training transmission correspond, respectively, to the second pseudo-random sequence of N/2 sub-symbols and the second N/2 arithmetic zero values.
15. A system for synchronizing a receiving of an orthogonal frequency division multiplexing (OFDM), the system comprising: an OFDM transmitter, configured to transmit a succession of OFDM information frames, each of the OFDM information frames carrying, on N sub-carriers, a block of OFDM symbols; and a training symbol insertion unit configured to insert N sub-symbol training prefixes between successive OFDM information frames, the training symbol insertion unit being further configured to generate, for each sub-symbol training prefix, a pseudo-random sequence of N/2 sub-symbols, a first half of the pseudo-random sequence being symmetrical to a second half of the pseudo-random sequence; form each of the N sub-symbol training prefix as an interleaving of N/2 arithmetic zero values interleaved with the generated pseudo-random sequence of N/2 sub-symbols, wherein the OFDM transmitter transmits the N sub-symbol training prefix as an N sub-carrier training transmission, in association with transmitting the OFDM frame, wherein: the N sub-carrier training transmission carries signal power on a first N/2 of the N sub-carriers and suppressed power on a second N/2 of the N sub-carriers, the first N/2 sub-carriers and the second N/2 sub-carriers being aligned at alternating positions in the frequency domain, and the first N/2 sub-carriers correspond to the pseudo-random sequence of N/2 sub-symbols and the second N/2 sub-carrier correspond to the arithmetic zero values.
16. The system of claim 15 , wherein: the training symbol insertion unit is further configured to generate each of the N/2 sub-symbols of the pseudo random sequence as a complex value, corresponding to an X-Y position in a complex plane, X being an in-phase component and Y being a quadrature component, and the N sub-carrier training transmission includes, for each pseudo-random sequence of N/2 sub-symbols included in the N sub-symbol training prefix, an amplitude-phase modulation of one of the first N/2 sub-carriers.
17. The system of claim 15 , wherein each N sub-carrier training transmission includes: inputting the N sub-symbol training prefix to an N-point inverse Fourier Transform process, and outputting a corresponding N time domain samples, and transmitting, as the N sub-carrier training transmission, the N time-domain samples.
18. The system of claim 17 , wherein: the N-point inverse Fourier Transform process outputs the corresponding N time domain samples in a parallel arrangement, and transmitting the N time-domain samples includes a parallel-to-serial re-configuration on the outputs Fourier Transform process into a serial stream of the N time domain samples, and a transmitting of the serial stream.
19. The system of claim 15 , wherein the training symbol insertion unit is further configured to form each of the N sub-symbol training prefixes by setting the N/2 arithmetic zero values at respective N/2 odd positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 even positions of the N sub-symbol training prefix, the N/2 even positions being interleaved with N/2 odd positions.
20. The system of claim 15 , wherein the training symbol insertion unit is further configured to form each of the N sub-symbol training prefixes by setting the N/2 arithmetic zero values at respective N/2 even positions of the N sub-symbol training prefix and the pseudo-random sequence of N/2 sub-symbols at respective N/2 odd positions of the N sub-symbol training prefix, the N/2 odd positions being interleaved with N/2 even positions.
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March 3, 2020
October 13, 2020
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